The evolved packet system (EPS) is an end-to-end system that provides a new radio access network, referred to as the evolved Universal Terrestrial Radio Access Network (E-UTRAN) or long term evolution (LTE), and a new packet core network, referred to as the evolved packet core (EPC), for broadband wireless data access. The EPC can also be used in conjunction with other radio access networks such as the GERAN (Global System for Mobile Communications (GSM) Enhanced Data rates for Global Evolution (EDGE) Radio Access Network) and the UTRAN. The EPC comprises a mobility management entity (MME), a packet data network (PDN) gateway (PDN-GW or shortly, P-GW) and a serving gateway (S-GW). In order to provide connectivity to packet data networks, end-to-end EPS bearers are established. An EPS bearer is a logical aggregate of one or more service data flows (SDFs) or internet protocol (IP) flows extending from a user equipment (UE) to a PDN gateway. All service data flows within a bearer receive the same level of quality of service (QoS). An EPS bearer is a collection of a radio bearer extending from a UE to an enhanced node B (eNB), an S1 bearer extending from an eNB to an S-GW across an S1 interface and an S5/S8 bearer extending from the S-GW to a P-GW across an S5/S8 interface. There is a one-to-one mapping between the radio, S1 and S5/S8 bearers.
It is expected that the number of so-called machine type communication devices (MTC devices) using similar applications and having, e.g., similar QoS needs will dramatically increase in the coming years. These devices behave often in a similar way, e.g. smart meters sending small amount of data once a day to a server, accessing the network almost simultaneously. Besides machine type devices, broadcast or multicast services such as mobile television (mobile TV) or video streaming and peer-to-peer services such as interactive gaming have often similar requirements on the usage of network resources. Establishing EPS bearers for each device requires an enormous amount of network resources and signaling. Also, performing policy/QoS control and charging individually for each device and each session at the P-GW leads to a huge load at the P-GW and policy control elements, such as e.g., a Policy and charging rules function (PCRF), present in the network.
Similar problems arise when several devices attached to the network need to be detached, e.g., due to network congestion leading to a network initiated detach or due to a device initiated detach. In either case, several bearers may need to be deactivated at the same time and this will lead to an enormous amount of signaling.